Storage lockers typically use mechanical locks to secure their contents; however, there has been a recent trend toward designing some lockers with electrically-operated mechanisms to enable electronic monitoring and/or control of the lockers.
Adding electronic control to lockers requires overcoming the difficulty of powering the locks. To power the locks either requires a hard-wired power connection that can pass through the hinge on the locker door (a solution that may lead to reliability problems due to flexing of the wires), or it requires energy storage within the locking mechanism. Relying on a stand-alone battery to operate a lock is a poor solution because when the battery runs out of charge, the locker can no longer be opened—a problem that becomes worse if the battery compartment is located inside the locker since a dead battery then becomes impossible to replace.
Many solutions have been proposed to avoid the possibility of unusable electronic lockers due to dead batteries inside the lock. These solutions either involve transmitting power directly to the lock through a battery-operated key that is brought into close proximity to the lock, or by inductively charging a battery inside the lock through a set of coils, one of which is on the locker door and another of which is adjacent to the first coil, but located on the fixed part of the locker (i.e. not the door). The inductive charging method requires running wires from the inductive coil at the edge of the door to the lock on the door. It also requires running wires to the other inductive coil which must be placed at the front of the locker adjacent to the door. The inductive charging method is limited to placing a coil next to the locker door due both to distance limitations of inductive charging and heating effects of metallic objects that are in close proximity to inductive coils.
The aforementioned solutions to avoiding dead batteries in lockers additional drawbacks. The use of battery-operated keys carries the possibility of the key not working if the battery in the key loses charge. The inductive charging method requires fitting inductive coils and running wires in very inconvenient places within the locker. Furthermore, the required additions of inductive charging make it a poor alternative to retrofit existing lockers with an electrically-controlled locking mechanism. In addition, all solutions that incorporate a battery inside the lock suffer from long-term reliability issues associated with battery life.